Exception java.lang.NoClassDefFoundError in Dynamic Web Application, Eclipse, JSF [duplicate] - eclipse

Question

This question already has answers here:
java.lang.NoClassDefFoundError: javax/servlet/jsp/jstl/core/Config
(2 answers)
Closed 7 years ago.
when I'm running my appication everything is ok to moment when I press the button and I'm redirecting to another xhtml page. Then eclipse console until I stop server display:
SEVERE: Servlet.service() for servlet [Faces Servlet] in context with path [/ChatAzure] threw exception [javax/servlet/jsp/jstl/core/Config] with root cause
java.lang.NoClassDefFoundError: javax/servlet/jsp/jstl/core/Config
at com.sun.faces.application.view.JspViewHandlingStrategy.executePageToBuildView(JspViewHandlingStrategy.java:345)
at com.sun.faces.application.view.JspViewHandlingStrategy.buildView(JspViewHandlingStrategy.java:154)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:100)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:928)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:298)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
I use:
eclipse, jsf2-1-7, jstl-1.2.jar, Tomcat v0.7.
I don't know what's wrong, I need help.

Answer 1

The mentioned class is part of JSTL. This is normally already provided by a full fledged Java EE container, but not in Tomcat as being a barebones JSP/Servlet container. You'd need to supply JSTL yourself along with the web application. It has ultimately to be placed in the webapp's runtime classpath.
You correctly mentioned jstl-1.2.jar (I assume that it's exactly the one as you could find in our JSTL wiki page), but this problem indicates that it has apparently not been placed at the right place. You need to place it in /WEB-INF/lib folder of the web project. This folder is covered by webapp's default runtime classpath. Nothing more needs to be done. If you have ever fiddled in the project's Build Path properties in an attempt to solve it, you should undo all those attempts.
Unrelated to the concrete problem: why are you still using legacy JSP? It has been deprecated and succeeded by Facelets (XHTML) since JSF 2.0. Make sure that you're reading up to date JSF 2.x resources and not JSF 1.x ones while learning JSF.